This invention relates in general to connectors for the support and retention of electrical conductors or cables in openings of electrical junction boxes or the like. It has been known from the prior art to provide a metallic connector with a compressive, hollow tubular body at one end and an annular flange at the other end. The annular flange serves the purpose of engaging the wall of the electrical box while the tubular body projects through the opening. After an electrical conductor or cable is passed axially through the tubular body of the connector, the tubular body is deformed by applying compressive pressure on opposing sides of the tubular body section. Thus, in the same motion, the connector is compressed upon and engages the cable, and the sides of the connector are projected outwardly, securing the connector to the outlet box and providing mechanical retention of the cable to the outlet box.
A major disadvantage of the presently known connectors of the type described is that they do not provide adequate closure of the opening into which the connector is installed so as to prevent foreign objects from entering. The annular flange portion of said connectors comprises a substantially flat form and is positioned in a plane perpendicular to the axis of the tubular body section. When the tubular body section is compressed around the cable the flange is, by its inherent nature, deformed from a substantially flat form into a compound concave surface.
This deformation of the annular flange presents two problems. First, and already mentioned, the deformation dislocates the flange from its intended position, raising a great percentage of its contact area from the wall of the electrical box and providing access for foreign objects to enter between the wall of the box and the annular flange. Second, the deformed flange is supported by only two points of contact with the box wall along the edge of the once flat flange. When the connector is compressed, the flange curls inward towards the tubular body being compressed, resulting in only two outer points of contact with the electrical box wall. FIG. 10, which depicts an installed connector of the type generally described by the prior art, illustrates this problem. When the secured cable is subjected to tensile stress, these two points of contact tend to cause previously compressed areas of the tubular body to pull apart, disengaging the cable and causing failure of the connection.
For the purposes of comparing the operation of connector 10 of the present invention with the operation of connectors described in the prior art, consider a typical connector 40 of the type generally described by the prior art, a side view of which is presented in FIG. 9. Connector 40 is comprised of a tubular body 42 with a flat annular flange 44 at one end. As shown in FIG. 10 flange 44, when installed, will be deformed into a compound concave shape having only two points of contact, 43 and 45, with the electrical box wall. This presents the problems of inadequate closure of the opening and uneven distribution of tensile stress, eventually resulting in failure of the connector. The connector of the present invention overcomes these problems by incorporating a flange which has an initial compound concave shape, and which is deformed into a desired flat, planar shape upon compression of the tubular body.
A rear view of an installed connector 40 of the type generally described by the prior art is presented in FIG. 11. Inadequate closure results both from inadequate closure of tubular body 42 around cable 46 and from deformation of flange 44 into a compound concave shape. The resulting open spaces which may allow introduction of foreign objects into the connector and electrical box are shown in FIG. 11 at A and B. These defects are corrected by the connector of the present invention.
The present invention overcomes these shortcomings of the prior art by providing a connector with a compressible tubular body and having a saddle-shaped compound concave flange curving away from the tubular body as its retaining surface. When the tubular body is compressed, it will pull the curved flange towards the tubular body. After compression, the flange will have assumed a flat planar surface of engagement with the wall of the electrical box into which it is installed. There is closure of the opening adequate to prevent foreign objects from entering and any tensile stress is distributed over the entire abutting surface of the flange, eliminating the tendency of the connector to pull apart under strain.